Liquid dispensing devices have been on the market for ages. Many of them rely on a pressurized gas raising the pressure to a level of about 0.5 to 1.5 bar above atmospheric in the interior of a container containing the liquid to be dispensed, in particular a beverage like beer or other carbonized beverages. The gas is either fed directly into the container containing the liquid like e.g., in U.S. Pat. No. 5,199,609 or between an external, rather stiff container and an inner, flexible vessel (e.g., a bag or a flexible bottle) containing the liquid to be dispensed, like in U.S. Pat. No. 5,240,144 (cf. appended FIG. 1(a)&(b)). Both applications have their pros and cons which are well known to the persons skilled in the art. The present invention applies equally to both types of delivery systems.
The compressed gas may be provided by a compressor, included in a specific appliance (cf. U.S. Pat. No. 5,251,787), or contained in a compressed gas bottle (cf. U.S. Pat. No. 5,383,576, FIG. 7). More recently, a market for disposable, stand alone, home appliances has been developing rapidly. For obvious technical and economic reasons, no compressor or large compressed gas bottle can be used in such disposable devices, and the propellant gas is then usually contained in a rather small pressurized cartridge closed by a cap or a membrane. The cap or membrane of these home dispensers may be pierced open in plant but, to avoid risks of leakage, it is usually preferred that the piercing of the closure be performed by the end-user prior to using the device for the first time. Examples of such devices can be found in EP149352, WO2007/145641, GB1427732, GB1163761, U.S. Pat. No. 3,372,838, and WO2006/128653.
The propellant gas stored in a bottle or cartridge is at a pressure much higher than the 0.5 to 1.5 bar required in the container to drive the dispensing of the beverage. It is therefore necessary to interpose between the gas bottle or cartridge and the container a pressure regulating valve for reducing the pressure of a propellant gas stored in a bottle or cartridge at a first, high pressure to a second, lower pressure suitable for driving the dispensing of the beverage. For beverage dispensing apparatuses, diaphragm regulating valves are usually preferred. A diaphragm valve comprises two chambers separated by a diaphragm or membrane. The first chamber comprises a fluid outlet in fluid communication with the container containing the liquid to be dispensed, as well as a fluid inlet which can be sealed by sealing means such as for example a ball attached to the membrane, adapted to seal said inlet when the pressure in the first chamber raises above a desired level. The second chamber comprises means for resiliently biasing the diaphragm such as to dislodge the sealing means from their seat when the pressure in the first chamber is below the desired level, and thus unsealing the inlet to allow pressurized gas to penetrate and thus raise the pressure to the desired level in the first chamber, Said means comprise for example a helicoidal spring.
The diaphragm or membrane (used here as synonyms) generally comprises an elastomeric peripheral section concentrically surrounding a central, more rigid section such as disclosed in WO94/29094. The central rigid section is designed to support the load of the diaphragm biasing means (e.g., helicoidal spring), whilst the elastomeric peripheral section allows for the required movements of the diaphragm and ensures gas tightness of the chambers when sandwiched between the walls defining the two chambers. Diaphragms made of a single material were proposed for certain applications, such as in FR2418352 in the field of pumps, or U.S. Pat. No. 4,978,478 in the field of carburators.
Diaphragm regulating valves are usually manufactured by producing two half shells defining the walls of the first and second chambers, which are then joined together, with the diaphragm sealingly sandwiched therebetween. Joining of the half shells can be achieved by many techniques known in the art, such as solvent welding, heat or vibration welding, gluing, and any mechanical fastening means, like screws, rivets, or snap fittings.
It can be seen that pressure regulating valves are relatively complex devices with a number of materials used for the various components: the housing of the two chambers, the diaphragm, and means for biasing the diaphragm, e.g., helicoidal spring. The manufacturing of a pressure regulating chamber often requires several assembly steps which further increase the cost of production.
US2003/0172971 discloses a valve for ultrapure water lines and for various chemical liquid lines allowing the reduction of eluted impurities and of contamination with chemical solutions by ensuring that all members of the valve in contact with the fluid flowing therethrough are made of a material having a high chemical resistance like PTFE. The members not in contact with the fluid, on the other hand, are made of another material, such as the ring 3 made of polypropylene and the O-rings made of an elastic rubber material. These expensive valves are suitable for highly demanding applications and are designed to last a long time and not particularly to facilitate recycling thereof, since this is not a major issue for such specialized items.
Recently, a market for stand-alone home appliances has been developing rapidly. In particular, some of these appliances are not meant to be reloaded after use with a new container and should be disposed of once the original container is empty. It is clear that the design of such all-in-one, ready-to-use, disposable appliances is severely cost driven, as the cost of the packaging and dispensing mechanism should not unreasonably outweigh the cost of the beverage to be dispensed, and sold in relatively small quantities in a container of a capacity of the order of 1 to 10 l, maybe up to 20 l. Furthermore, recycling of the components of disposable appliances is a problem which cannot be overlooked nowadays. A major problem with recycling is separating the appliance components made of differing materials.
The existing pressure regulating valves are not adapted to the requirements of these new types of dispensers. There therefore remains a need for providing a low cost albeit reliable pressure regulating valve, which is easy to recycle.